The father of a British backpacker missing in Cambodia has said he fears she has been abducted.

Amelia Bambridge, from Worthing, West Sussex, was last seen on the island of Koh Rong late on Wednesday night.

Staff at Police Beach, a private venue that stages regular events, found Ms Bambridge’s purple rucksack, containing her purse, phone and bank cards, the following morning.

Around 150 volunteers and Cambodian police are involved in searches of the shoreline and jungle for the missing 21-year-old.

Her father Phil Bambridge, who has travelled to the island, said he believed she had been “taken”.

He told Sky News: “I don’t think she’s had an accident. If she’d had an accident she would have been found by now.”

Amelia Bambridge was last seen on the island of Koh Rong late on Wednesday night. Credit: Twitter/Georgie Bambridge

Mr Bambridge said that, having viewed CCTV, he believed she had been lost inland.

He said: “So we sort of knew from this here we were getting to fixed times and where she got there. I don’t think she’s in the sea, I think she’s inland somewhere.”

Major general Chuon Narin, police chief of coastal Preah Sihanouk province, said divers, police, navy personnel, local volunteers and foreigners were taking part in the searches.

He told AP: “As of now, the searchers have no news about her whereabouts and they have expanded the area they are searching to make sure all possible sites are checked.

“I can’t say whether Bambridge was killed or got lost in the island’s jungle.”

Ms Bambridge’s brother Harry wrote on Facebook on Sunday: “So I’ve landed in Cambodia, in a taxi to attempt to make the last ferry to the island, which is a five hour taxi.

“I’m totally overwhelmed with everyone’s support and I can’t thank you all enough.”

In a different post, he added: “I seriously believe there is still hope for her to be found alive.”

Ms Bambridge set off on her trip on September 27, when she flew to Vietnam, her family said.

They were alerted to her disappearance after she failed to check out of the Nest Beach Club hostel after she was last seen at a beach party.

Her passport remained at the hostel.